Vehicle manufacturers are increasingly replacing mechanical linkages in vehicles with sensors and electromechanical devices to reduce weight and cost. For example, sensors are replacing mechanical linkages to detect positions of user operated devices such as accelerator, clutch, and brake pedals. Signals are transmitted from the sensors to controllers and/or electromechanical devices in the vehicle. For example, a signal from an accelerator pedal may be transmitted to an actuator in the electronic throttle body to adjust the position of the throttle blade. Additionally, a throttle position sensor detects the position of the throttle blade and transmits a signal to an engine control module.
In cases where mechanical linkages are at least partially eliminated, multiple sensors are commonly used to perform redundant measurements and ensure system accuracy. For example, some manufacturers use analog position sensors that are based on a resistive ink or paste that is deposited on a non-conducting substrate. Other manufacturers use application specific integrated circuits (ASICs) in combination with sensors. The sensors typically include hall effect or inductively coupled sensors. The ASICs receive analog signals from the sensors and output pulse width modulated (PWM) or other types of signals.
Referring to FIG. 1, a vehicle control system 10 includes a sensor module 12 and a control module 14. For example, the sensor module 12 may be an ASIC. The sensor module 12 includes first and second signal conversion modules 16 and 18, respectively. The signal conversion modules 16 and 18 receive first and second position signals 20 and 22, respectively. The position signals 20 and 22 are from first and second position sensors that detect a position of a device. For example, the device may be an accelerator pedal, brake pedal, clutch pedal, or a throttle blade in a vehicle. The position signals 20 and 22 indicate first and second position values of the device.
The signal conversion modules 16 and 18 convert the position values into first and second analog waveforms 24 and 26, respectively. The signal conversion modules 16 and 18 include mechanical adjustments that adjust characteristics of the analog waveforms 24 and 26. For example, the signal conversion modules 16 and 18 of FIG. 1 include potentiometers that adjust the amplitude and/or duty cycle of the analog waveforms 24 and 26 given a fixed frequency when a position of the device is fixed.
The control module 14 receives the analog waveforms 24 and 26 and decodes the analog waveforms 24 and 26 to recover the first and second position values. The sensor module 12 may use one or multiple shared reference voltages for each of the signal conversion modules 16 and 18. The first and second position values provide an opportunity for the vehicle control system 10 to perform redundant position sensing of devices. However, as the number of sensors increases, the number of wires and overall cost increases.